The present invention relates to computer apparatus. More particularly, it relates to an apparatus and a method for dividing a number by a constant.
In computer apparatus, data is stored in the memory portion of the computer in accordance with a predetermined format. Under such circumstances, the memory may be addressed in accordance with straightforward addressing procedures. On the other hand, it is not unusual that data or instructions are received by the computer with the address information in a different format. For example, in one such format the address information may be in the form of a count of six-bit characters. In such a case, in order to render that address usable, the address information must be divided by a factor of six. Such a transaction in computers heretofore have been accomplished by effecting the division in arithmetic logic units of the computer processor.
On other occasions, the information may be received as a bit count or a so-called bit-string format of information. While the bit string type of information is received as a continuous stream of bits of data, as many as 2.sup.24 bits, it is recorded in the memory in the form of 36-bit words each consisting of four 9-bit bytes. In order to find the specific address identified by the bit-count number with respect to the words and bytes stored in the memory, it is necessary to divide the bit-count number by 36 to find the word then further divide the word and find the byte and bit position of the start of the memory transaction. Again such division is usually accomplished by referring the bit-count number to the arithmetic logic unit of the computer to effect the necessary division.
The referring of the 6-bit character count or the bit-string count number to the arithmetic logic unit of the computer to effect the necessary divisions to find the proper address for the transaction, is a necessarily slow process which impedes the data handling rate of the computer as well as tying up the arithmetic logic unit for the purpose of identifying the proper address.